kuiper belt Archives

February 19, 2015December 23, 2015 by Tim Reyes

A Recipe for Returning Pluto to Full Planethood

ILLUSTRATION IS RESERVED - DO NOT USE. The eight planets of the Solar System and the dwarf planet Pluto. For many astronomers and planetary scientists Pluto's status remains an open question. Redefining what is a planet could return Pluto to the fold - 9 planets and also open the door for many more. Insets from upper left, clockwise: Clyde Tombaugh, Mike Brown, Alan Stern, Gerard Kuiper.(Credit: NASA, Judy Schmidt, Björn Jónsson)

A storm is brewing, a battle of words and a war of the worlds. The Earth is not at risk. It is mostly a civil dispute, but it has the potential to influence the path of careers. In 2014, a Harvard led debate was undertaken on the question: Is Pluto a planet. The impact of the definition of planet and everything else is far reaching – to the ends of the Universe.

It could mean a count of trillions of planets in our galaxy alone or it means leaving the planet Pluto out of the count – designation, just a dwarf planet. This is a question of how to classify non-stellar objects. What is a planet, asteroid, comet, planetoid or dwarf planet? Does our Solar System have 8 planets or some other number? Even the count of planets in our Milky Way galaxy is at stake.

"Dawn arising." The latest image of Ceres - February 12, 2015 - by the Dawn spacecraft from 80,000 km. With icy deposits pock marking its surface, a possible reservoir of water below its surface, is Ceres a planet, dwarf planet, an asteroid or all three? (Credit: NASA/Dawn) — “Dawn arising.” The latest image of Ceres – February 12, 2015 – by the Dawn spacecraft from 80,000 km. With icy deposits pock marking its surface, a possible reservoir of water below its surface, is Ceres a planet, dwarf planet, an asteroid or all three? (Credit: NASA/Dawn)

Not to dwell on the Harvard debate, let it be known that if given their way, the debates outcome would reset the Solar System to nine planets. For over eight years, the solar system has had eight planets. During the period 1807 to 1845, our Solar System had eleven planets. Neptune was discovered in 1846 and astronomers began to discover many more asteroids. They were eliminated from the club. This is very similar to what is now happening to Pluto-like objects – Plutoids. So from 1846 to 1930, there were 8 planets – the ones as defined today.

The discoverer of Pluto - Clyde Tombaugh in the 1930s and again with homebuilt telescope in the 1990s that earned him an assignment at Lowell Observatory - discover Planet X. Cremated remains of Clyde are attached to the New Horizons space probe now approaching the dwarf planet Pluto. — The discoverer of Pluto – Clyde Tombaugh in the 1930s and again with homebuilt telescope in the 1990s that earned him an assignment at Lowell Observatory – discover Planet X. The cremated remains of Clyde are attached to the New Horizons space probe that is now approaching the dwarf planet Pluto.

In 1930, a Kansas farm boy, Clyde Tombaugh, hired by Lowell Observatory discovered Pluto and for 76 years there were 9 planets. In the year 2006, the International Astronomical Union (IAU) took up a debate using a “democratic process” to accept a new definition of planet, define a new type – dwarf planet and then set everything else as “Small Bodies.” If your head is spinning with planets, you are not alone.

All two body systems have a barycenter, the shared point in space around which they orbit. Pluto and Charon’s happens to be between both bodies due to their proximity and similar mass. (Credit: NASA/New Horizons)

Two NASA missions were launched immediately before and after the IAU announcement took affect. The Dawn mission suddenly was to be launched to an asteroid and a dwarf planet and the New Horizons had rather embarked on a nine year journey to a planet belittled to a dwarf planet – Pluto. Principal Investigator, Dr. Alan Stern was upset. Furthermore, from the discoveries of the Kuiper mission and other discoveries, we now know that there are hundreds of billions of planets in our Milky Way galaxy; possibly trillions. The present definition excludes hundreds of billions of bodies from planethood status.

There are two main camps with de facto leaders. One camp has Dr. Mike Brown of Caltech and the other, Dr. Stern of the Southwest Research Institute (SWRI) as leading figures. A primary focus of Dr. Brown’s research is the study of trans-Neptunian objects while Dr. Sterns’s activities are many but specifically, the New Horizons mission which is 6 months away from its flyby of Pluto. Consider first the IAU Resolution 5A that its members approved:

(1) A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.

This is our starting point – planet, dwarf planet, everything else. Consider “everything else”. This broad category includes meteoroids, asteroids, comets and planetesimals. Perhaps other small body types will arise as we look more closely at the Universe. Within the category, there is now a question of what is an asteroid and what is a comet. NASA’s flybys of comets and now ESA’s Rosetta at 67P/Churyumov–Gerasimenko are making the delineation between the two types difficult. The difference between a meteoroid and an asteroid is simply defined as less than or greater than one meter in size, respectively. So the Chelyabinsk event absolutely involved a small asteroid – about 20 meters in diameter. Planetesimals are small bodies in a solar nebula that are the building blocks of planets but they could lead to the creation of all the other types of small bodies.

Dr. Alan Stern, project scientist for New Horizons and Neil deGrasse Tyson discuss the New Horizons spacecraft in the mission operations center at JHU/APL. The interview was for a NOVA special (12/14/2011), the Pluto Files, about a Kansas farm boy, a missing planet and the 70 years of astronomical discoveries leading to the present day. (Credit: JHU/APL,PBS)

Putting aside the question of “Small Bodies” and its sub-classes, what should be the definition of planet and dwarf planet? These are the two terms that demoted Pluto and raised Ceres to dwarf planet. It is also interesting to note how Resolution 5A is meant exclusively for our Solar System. In 2006, there were not thousands of exo-planets but just a few dozen extreme cases but nevertheless, the IAU did not choose to extend the definition to “stars” but rather just in reference to our pretty well known star, the Sun.

Recall Tim Allen’s movie, “The Santa Clause”. Clauses can cause a heap of trouble. The IAU has such a clause – Clause C which has caused much of the present controversy around the definition of planets. Clause (c) of Resolution 5A: “has cleared the neighborhood around its orbit.” This is the Pluto killer-clause which demoted it to dwarf planet status and reduced the number of planets in our solar system to eight. In a sense, the IAU chose to cauterize a wound, a weakness in the definitions, that if left unchanged, would have led to who knows how many planets in our Solar System.

The question of what is Pluto is open for public discussion so armed with enough knowledge to be dangerous, the following is my proposed alternative to the IAU’s that are arguably an improvement. The present challenge to Pluto’s status lies in the Kuiper Belt and Oort Cloud. Such belts or clouds are probably not uncommon throughout the galaxy. Plutoids are the 500 lb gorilla in the room.

Two spacecraft, Dawn and New Horizon will reach their final objectives in 2015 - Dwarf Planets - Ceres and Pluto. (Credit: NASA, Illustration - T.Reyes) — Two spacecraft, Dawn and New Horizon will reach their final objectives in 2015 – Dwarf Planets – Ceres and Pluto. (Credit: NASA, Illustration – T.Reyes)

This year, as touted by the likes of Planetary Society, Universe Today and elsewhere, is the year of the dwarf planet. How remarkable and surprising will the study of Ceres, Pluto and Charon by NASA spacecraft be? There is a strong possibility that after the celestial dust clears and data analysis is published, the IAU will take on the challenge again to better define what is a planet and everything else. It is impossible to imagine that the definitions can remain unchanged for long. Even now, there is sufficient information to independently assess the definitions and weigh in on the approaching debate. Anyone or any group – from grade schools to astronomical societies – can take on the challenge.

To encourage a debate and educate the public on the incredible universe that space probes and advanced telescopes are revealing, what follows is one proposed solution to what is a planet and everything else.

planet: is a celestial body that a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium – nearly round shape, b) has a differentiated interior as a result of its formation c) has insufficient mass to fuse hydrogen in its core, d) does not match the definition of a moon.

minor planet: is a planet with a mass less than one Pluto mass and does not match the definition of a moon.

inter-Stellar (minor) planet: is a (minor) planet that is not gravitationally bound to a stellar object.

binary (minor) planet: is a celestial body that is orbiting another (minor) planet for which the system’s barycenter resides above the surface of both bodies.

These definitions solve some hairy dilemmas. For one, planets orbit around the majority of most stars in the Universe, not just the Sun as Resolution 5A was only intended. Planets can also exist gravitationally not bound to a star – the result of it own molecular cloud collapse without a star or expulsion from a stellar system. One could specify gravitational expulsion however, it is possible that explosive events occur that cause the disintegration of a star and its binding gravity or creates such an impulse that a planet is thrusted out of a stellar system. Having an atmosphere certainly doesn’t work. Astronomers are already anticipating Mars or Earth-sized objects deep in the Oort cloud that could have no atmosphere – frozen out and also despite their size, not be able to “clear their neighborhood.”

An animation (above) of Kepler mission planet candidates compiled by Jeff Thorpe. Kepler and other exoplanet projects are revealing that the properties of planets – orbits, size, temperature, makeup – are all extreme. Does Pluto represent one of those extremes – the smallest of planets? (Credit: NASA/Kepler, Jeff Thorp)

The need to create a lower-end limit to what is a planet reached a near fever pitch with the discovery of a Trans-Nepturnian Object (TNO) in 2005 that is bigger than Pluto – Eris. Dr. Michael Brown of Caltech and his team led in the discovery of bright large KBOs. There was not just Eris but many of nearly the same size as Pluto. So without clause (c), one would be left with a definition for planet that could allow the count of planets in our Solar System to rise into the hundreds maybe even thousands. This would become a rather unmanageable problem; the number of planets rising year after year and never settled and with no means to make reasonable comparisons between planetary systems throughout our galaxy and even the Universe.

The book that tells the story of discovery - trans-Neptunian objects (TNO) that led to the downfall of Pluto from full planethood to that of a dwarf. The 2006 IAU decision was a pre-emptive strike to stave off a proliferation of planets in our system. It worked but "killed" Pluto. Did it have it coming? Dr. Brown also agrees that the present definition of planet is flawed and incomplete. (Photo Credits: Caltech/M.Brown) — The book that tells the story of discovery – trans-Neptunian objects (TNO) that led to the downfall of Pluto from full planethood to that of a dwarf. The 2006 IAU decision was a pre-emptive strike to stave off a proliferation of planets in our system. It worked but “killed” Pluto. Did it have it coming? Dr. Brown also agrees that the present definition of planet is flawed and incomplete. (Photo Credits: Caltech/M.Brown)

Two more celestial body types follow that are proposed to round out the set.

moon: is a celestial body that a) orbits a (minor) planet and b) for which the barycenter of its orbit is below the surface of its parent (minor) planet.

This creates the possibility of a planet-moon system such that its barycenter is above the surface of the larger body. Pluto and Charon are the most prominent case in our Solar System. In such cases, if one body meets the criteria of a (minor)planet, then the other body can also be assessed to determine if it is also a (minor) planet and the pair as binary (minor) planets. If the primary body was a minor planet, it is possible that the barycenter could be above its surface but the secondary body does not meet all the criteria of a minor planet, specifically “differentiated interior”.

The definition of moon is compounded by the existence of, for example, asteroids with moons. For such objects, the smaller object is defined as a satellite.

Satellite: is a celestial body that a) orbits another celestial body, b) whose parent body is not a (minor) planet.

Another permissible term is moonlet which could be used to describe both very small moons such as those found in the Jovian and Saturn systems or a small body orbiting an asteroid or comet. Moonlet could replace satellite.

The discriminator between planet and moon is not mass but simply whether the celestial body orbits a (minor) planet and the barycenter resides inside the larger body. The definition of moon excludes the possibility of a planet orbiting another planet except in the special case of binary (minor) planet.

Defining a lower size limit to “Planet” is necessary to compare stellar systems and classify. A limit based on the body’s average surface pressure and temperature or the surface gravity could define a limit. While they could, they are not practical because of the extremes and diverse combinations of conditions. Strange objects would fall through the cracks.

Removing clause (c) – “has cleared the neighborhood around its orbit” – will avoid a future conflict such as a very low mass star with a plutoid-sized object or smaller, in a close orbit that has cleared its neighborhood.

Additionally, choosing to declare that Pluto becomes the “standard weight” that differentiates minor planet from planet sets a precedent. In an era in which computers measure and tally the state of our existence, setting this limit to include Pluto and return it as the ninth planet of our Solar System, is, in a small but significant way, a re-declaration of our humanity. Soon we will be challenged by artificial intelligence greater than ours; we are already have. Where will we stand our ground?

Forget about Pluto for a moment. Should Eris be our tenth Planet? Like Pluto it has a prominent moon- Dysnomia. Human perception and conceptions of the Universe have shaped our view of the Solar System. The Ptolemaic system (Earth centered), Kepler's Harmonic Spheres, even the fact that ten digits reside on our hands impact our impression of the Solar System (Photo Credits:NASA/ESA and M. Brown / Caltech) — Forget about Pluto for a moment. Should Eris be our tenth planet? Like Pluto it has a prominent moon- Dysnomia. Human perception and conceptions of the Universe have shaped our view of the Solar System. The Ptolemaic system (Earth centered), Kepler’s Harmonic Spheres, even the fact that ten digits reside on our hands impact our impression of the Solar System (Photo Credits:NASA/ESA and M. Brown / Caltech)

The consequences of this proposed set of definitions, makes Ceres a minor planet and no longer an asteroid. Many trans-Neptunian objects discovered in this century become minor planets. Of the known TNOs only Pluto and Eris meets the criteria of planet.The dwarf planet Eris would become the tenth planet. Makemake, Sedna, Quaoar, Orcus, Haumea would be minor planets. By keeping Pluto a planet and defining it as the standard bearer, only one new planet must be declared. Surely, more will be found, very distant, in odd elliptical and tilted orbits. The count of planets in our solar system could rise by 10, 20 maybe 50 and perhaps this would make the definition untenable but maybe not. So be it. New Horizons will fly by a dwarf planet in July but this should mark the beginning of the end of the present set of definitions.

Three perspectives of a ten planet Solar System. No longer Earth centered, or with harmonic spheres but now with planets outside the ecliptic plane and growing. How many planets would be too many? (Credits: Wikimedia, T.Reyes)

This set of definitions defines a set of celestial bodies that consistently covers the spectrum of known bodies. There is the potential of exotic celestial objects that are spawned from cataclysmic events or from the unique conditions during the early epochs of the Universe or from remnants of old or dying stellar objects. Their discovery will likely trigger new or revised definitions but these definitions are a good working set for the time being. Ultimately, it is the decision of the IAU but the sharing of knowledge and the democratic processes that we cherish permits anyone to question and evaluate such definitions or proclamations.To all that share an interest in Pluto as or as not a planet raise your hand and be heard.

A video from 2014 by Kurz Gesagt describing the Pluto-Charon system. Is this a binary planet system or one of the “dwarf” variety?

It Looks Like These Are All the Bright Kuiper Belt Objects We’ll Ever Find

The presently known largest trans-Neptunian objects (TNO) - are likely to be surpassed by future discoveries. Which of these trans-Neptunian objects (TNO) would you call planets and which "dwarf planets"? (Illustration Credit: Larry McNish, Data: M.Brown)

The self-professed “Pluto Killer” is at it again. Dr. Michael Brown is now reminiscing about the good old days when one could scour through sky survey data and discover big bright objects in the Kuiper Belt. In his latest research paper, Brown and his team have concluded that those days are over.

Ten years ago, Brown discovered what is now known as the biggest Kuiper Belt object – Eris. Brown’s team found others that rivaled Pluto in size and altogether, these discoveries led to the demotion of Pluto to dwarf planet. Now, using yet another sky survey data set but with new computer software, Brown says that its time to move on.

Instigators of the big heist - David Rabinowitz, Brown and Chad Trujillo, left to right. The researchers discovered dozens of Kuiper Belt objects (KBO) including six of the eight largest KBOs including the largest, Eris. — Instigators of the big heist – Rabinowitz, Brown and Trujillo, left to right. The researchers co-discovered dozens of Kuiper Belt objects (KBO) including nine of the ten largest KBOs including the largest, Eris.

Like the famous Bugs Bunny cartoon, its no longer Rabbit Season or Duck Season and as Bugs exclaims to Elmer Fudd, there is no more bullets. Analyzing seven years worth of data, Brown and his team has concluded we are fresh out of Pluto or Charon-sized objects to be discovered in the Kuiper Belt. But for Dr. Brown, perhaps it now might be Oort Cloud season.

His latest paper, A Serendipitous All Sky Survey For Bright Objects In The Outer Solar System, in pre-print, describes the completion of analysis of two past sky surveys covering the northern and southern hemisphere down to 20 degrees in Galactic latitude. Using revised computer software, his team scoured through the data sets from the Catalina Sky Survey (CSS) and the Siding Spring Survey (SSS). The surveys are called “fast cadence surveys” and they primarily search for asteroids near Earth and out to the asteroid belt. Instead Brown’s team used the data to look at image frames spaced days and months apart.

Update: In a Twitter communique, Dr. Brown stated, “I would say we’re out of BRIGHT ones, not big ones. Could be big ones lurking far away!” His latest work involved a southern sky survey (SSS) to about magnitude 19 and the northern survey (CSS) to 21. Low albedo (dark) and more distant KBOs might be lurking beyond the detectability of these surveys that are in the range of Charon to Pluto in size.

Animation showing the movement of Eris on the images used to discover it. Eris is indicated by the arrow. The three frames were taken over a period of three hours. (Credit: Brown, et al.) — Animation showing the movement of Eris on the images used to discover it. Eris is indicated by the arrow. The three frames were taken over a period of three hours. More images over several weeks were necessary to determine its orbit.(Credit: Brown, et al.)

Objects at Kuiper Belt distances move very slowly. For example, Pluto orbits the Sun at about 17,000 km/hr (11,000 mph), taking 250 years to complete one orbit. These are speeds that are insufficient to maintain ven a low-Earth orbit. Comparing two image frames spaced just hours apart will find nearby asteroids moving relative to the star fields but not Kuiper belt objects. So using image frames spaced days, weeks or even months apart, they searched again. Their conclusion is that all the big Kuiper belt objects have been found.

The only possibility of finding another large KBO lies in a search of the galactic plane which is difficult due to the density of Milky Way’s stars in the field of view. The vast number of small bodies in the Kuiper belt and Oort Cloud lends itself readily to statistical analysis. Brown states that there is a 32% chance of finding another Pluto-sized object hiding among the stars of the Milky Way.

Artists concept of the view from Eris with Dysnomia in the background, looking back towards the distant sun. Credit: Robert Hurt (IPAC)

Dr. Brown also released a blog story in celebration of the discovery of the largest of the Kuiper Belt objects, Eris, ten years ago last week. Ten years of Eris, reminisces about the great slew of small body discoveries by Dr. Brown, Dr. Chad Trujillo of Gemini Observatory and Dr. David Rabinowitz of Yale Observatory.

Brown encourages others to take up this final search right in the galactic plane but apparently his own intentions are to move on. What remains to be seen — that is, to be discovered — are hundreds of large “small” bodies residing in the much larger region of the Oort Cloud. These objects are distributed more uniformly throughout the whole spherical region that the Cloud defines around the Sun.

Furthermore, Dr. Brown maintains that there is a good likelihood that a Mars or Earth-sized object exists in the Oort Cloud.

Small bodies within our Solar System along with exo-planets are perhaps the hottest topics and focuses of study in Planetary Science at the moment. Many graduate students and seasoned researchers alike are gravitating to their study. There are certainly many smaller Kuiper belt objects remaining to be found but more importantly, a better understanding of their makeup and origin are yet to be revealed.

Artist's concept of the Dawn spacecraft at the protoplanet Ceres Illustration of Dawn's approach phase and RC3 orbit This artist’s concept of NASA’s Dawn spacecraft shows the craft orbiting high above Ceres, where the craft will arrive in early 2015 to begin science investigations. (Image credit: NASA/JPL-Caltech) — Artist’s concept of the Dawn spacecraft at the protoplanet Ceres Illustration of Dawn’s approach phase and RC3 orbit This artist’s concept of NASA’s Dawn spacecraft shows the craft orbiting high above Ceres, where the craft will arrive in early 2015 to begin science investigations. (Image credit: NASA/JPL-Caltech)

Presently, the Dawn spacecraft is making final approach to the dwarf planet Ceres in the Asteroid belt. The first close up images of Ceres are only a few days away as Dawn is now just a couple of 100 thousand miles away approaching at a modest speed. And much farther from our home planet, scientists led by Dr. Alan Stern of SWRI are on final approach to the dwarf planet Pluto with their space probe, New Horizons. The Pluto system is now touted as a binary dwarf planet. Pluto and its moon Charon orbit a common point (barycenter) in space that lies between Pluto and Charon.

So Dr. Brown and team exits stage left. No more dwarf planets – at least not soon and not in the Kuiper belt. Will that upstage what is being called the year of the Dwarf Planet?

But next up for close inspection for the first time are Ceres, Pluto and Charon. It should be a great year.

The relative sizes of the inner Solar System, Kuiper Belt and the Oort Cloud. (Credit: NASA, William Crochot)

References:

A Serendipitous All Sky Survey For Bright Objects In The Outer Solar System

Ten Years of Eris

2015, NASA’s Year of the Dwarf Planet, Universe Today

What is the Kuiper Belt?, Universe Today

January 7, 2015December 23, 2015 by Tim Reyes

The Dark Energy Survey Begins to Reveal Previously Unknown Trans-Neptunian Objects

An artist's concept of a trans-Neptunian object(TNOs). The distant sun is reduced to a bright star at a distance of over 3 billion miles. The Dark Energy Survey (DES) has now released discovery of more TNOs. (Illustration Credit: NASA)

Sometimes when you stare at something long enough, you begin to see things. This is not the case with optical sensors and telescopes. Sure, there is noise from electronics, but it’s random and traceable. Stargazing with a telescope and camera is ideal for staring at the same patches of real estate for very long and repeated periods. This is the method used by the Dark Energy Survey (DES), and with less than one percent of the target area surveyed, astronomers are already discovering previously unknown objects in the outer Solar System.

The Dark Energy Survey is a five year collaborative effort that is observing Supernovae to better understand the structures and expansion of the universe. But in the meantime, transient objects much nearer to home are passing through the fields of view. Trans-Neptunian Objects (TNOs), small icy worlds beyond the planet Neptune, are being discovered. A new scientific paper, released as part of this year’s American Astronomical Society gathering in Seattle, Washington, discusses these newly discovered TNOs. The lead authors are two undergraduate students from Carleton College of Northfield, Minnesota, participating in a University of Michigan program.

The Palomar Sky Survey (POSS-1, POSS-2), the Sloan Digital Sky Survey, and every other sky survey have mapped not just the static, nearly unchanging night sky, but also transient events such as passing asteroids, comets, or novae events. The Dark Energy Survey is looking at the night sky for structures and expansion of the Universe. As part of the five year survey, DES is observing ten select 3 square degree fields for Type 1a supernovae on a weekly basis. As the survey proceeds, they are getting more than anticipated. The survey is revealing more trans-Neptunian objects. Once again, deep sky surveys are revealing more about our local environment – objects in the farther reaches of our Solar System.

DES is an optical imaging survey in search of Supernovae that can be used as weather vanes to measure the expansion of the universe. This expansion is dependent on the interaction of matter and the more elusive exotic materials of our Universe – Dark Energy and Dark Matter. The five year survey is necessary to achieve a level of temporal detail and a sufficient number of supernovae events from which to draw conclusions.

In the mean time, the young researchers of Carleton College – Ross Jennings and Zhilu Zhang – are discovering the transients inside our Solar System. Led by Professor David Gerdes of the University of Michigan, the researchers started with a list of nearly 100,000 observations of individual transients. Differencing software and trajectory analysis helped identify those objects that were trans-Neptunian rather than asteroids of the inner Solar System.

While asteroids residing in the inner solar system will pass quickly through such small fields, trans-Neptunian objects (TNOs) orbit the Sun much more slowly. For example, Pluto, at an approximate distance of 40 A.U. from the Sun, along with the object Eris, presently the largest of the TNOs, has an apparent motion of about 27 arc seconds per day – although for a half year, the Earth’s orbital motion slows and retrogrades Pluto’s apparent motion. The 27 arc seconds is approximately 1/60th the width of a full Moon. So, from one night to the next, TNOs can travel as much as 100 pixels across the field of view of the DES survey detectors since each pixel has a width of 0.27 arc seconds.

Composite Dark Energy Camera image of one of the sky regions that the collaboration will use to study supernovae, exploding stars that will help uncover the nature of dark energy. The outlines of each of the 62 charge-coupled devices can be seen. This picture spans 2 degrees across on the sky and contains 520 megapixels. (Credit: Fermilab)

The scientific sensor array, DECam, is located at Cerro Tololo Inter-American Observatory (CTIO) in Chile utilizing the 4-meter (13 feet) diameter Victor M. Blanco Telescope. It is an array of 62 2048×4096 pixel back-illuminated CCDs totaling 520 megapixels, and altogether the camera weighs 20 tons.

A simple plot of the orbit of one of sixteen TNOs discovered by DES observatrions. (Credit: Dark Energy Detectives) — A simple plot of the orbit of one of sixteen TNOs discovered by DES observations. (Credit: Dark Energy Detectives)

With a little over 2 years of observations, the young astronomers stated, “Our analysis revealed sixteen previously unknown outer solar system objects, including one Neptune Trojan, several objects in mean motion resonances with Neptune, and a distant scattered disk object whose 1200-year orbital period is among the 50 longest known.”

Object 2013 TV158 is one of the objects discovered by Carleton College and University of Michigan team. Observed more than a dozen times over 10 months, the animated gif shows two image frames from August, 2014 taken two hours apart. 2013 TV158 takes 1200 years to orbit the Sun and is likely a few hundred kilometers across (about the size of the Grand Canyon. (Credit: Dark Energy Detectives) — Object 2013 TV158 is one of the objects discovered by the Carleton College and University of Michigan team. Observed more than a dozen times over 10 months, the animated gif shows two image frames from August 2014 taken two hours apart. 2013 TV158 takes 1200 years to orbit the Sun and is likely a few hundred kilometers across – about the size of the Grand Canyon. (Credit: Dark Energy Detectives)

“So far we’ve examined less than one percent of the area that DES will eventually cover,” says Dr. Gerdes. “No other survey has searched for TNOs with this combination of area and depth. We could discover something really unusual.”

Illustration of colour distribution of the trans-Neptunian objects. The horizontal axis represents the difference in intensity between visual (green & yellow) and blue of the object while the vertical is the difference between visual and red. The distribution indicates how TNOs share a common origin and physical makeup as well as common weathering in space. Yellow objects serve as reference: Neptune's moon Triton, Saturn's moon Phoebe, centaur Pholus, and the planet Mars. The objects color represents the hue of the object. The size of the objects are relative where the larger objects are more accurate estimates and smaller objects are simply based on absolute magnitude. (Credit: Wikimedia, Eurocommuter) — Illustration of color distribution of the trans-Neptunian objects. The horizontal axis represents the difference in intensity between visual (green & yellow) and blue of the object, while the vertical axis is the difference between visual and red. The distribution indicates how TNOs share a common origin and physical makeup, as well as common weathering in space. Yellow objects serve as reference: Neptune’s moon Triton, Saturn’s moon Phoebe, centaur Pholus, and the planet Mars. The object’s color represents the hue of the object. The size of the objects are relative – the larger objects are more accurate estimates, while smaller objects are simply based on absolute magnitude. (Credit: Wikimedia, Eurocommuter)

What does it all mean? It is further confirmation that the outer Solar System is chock-full of rocky-icy small bodies. There are other examples of recent discoveries, such as the search for a TNO for the New Horizons mission. As New Horizons has been approaching Pluto, the team turned to the Hubble space telescope to find a TNO to flyby after the dwarf planet. Hubble made short shrift of the work, finding three that the probe could reach. However, the demand for Hubble time does not allow long term searches for TNOs. A survey such as DES will serve to uncover many thousands of more objects in the outer Solar System. As Dr. Michael Brown of Caltech has stated, there is a fair likelihood that a Mars or Earth-sized object will be discovered beyond Neptune in the Oort Cloud.

References:
Observation of new trans-Neptunian Objects in the Dark Energy Survey Supernova Fields
Undergraduate Researchers Discover New Trans-Neptunian Objects
Dark Sky Detectives

For more details on the Dark Energy Survey: DES Website

November 10, 2014December 23, 2015 by Elizabeth Howell

‘Naked’ Comets Could Expose Solar System’s Ancient Origin Story

Two objects with comet-like orbits flew through the solar system in 2013 and 2014, but with little to no activity on their surfaces. At left is C/2013 P2 Pan-STARRS and at right, C/2014 S3 Pan-STARRS. Credit: University of Hawaii Institute for Astronomy

What’s a comet that doesn’t look like a comet? The question sounds contradictory, but astronomers believe these objects exist. As comets pass through the solar system, they bleed ice and dust as the Sun’s effects wash over their small bodies. Over time, some of the objects can keep going like ghost ships — just without the ices that used to produce a show.

There already is a class of objects called damocloids that are believed to be extinct comets, but scientists believe they have found something new with two mysterious visitors — what they call “naked” comets — from the outer Solar System.

The two objects originate from an area that astronomers term the Oort Cloud, a hypothetical collection of icy bodies that orbit as far away as 100,000 times the Earth-Sun distance (astronomical unit). Gravitational influences then kick the objects in towards the Sun and they commence orbits that can last millions of years.

When Jan Oort first proposed this concept in the 1950s, he said that some of the objects there could have only a tiny layer of ice that would immediately evaporate during the first pass in near the Sun. That’s what astronomers think they are seeing in objects C/2013 P2 Pan-STARRS and C/2014 S3 Pan-STARRS.

The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets - the Oort Cloud. Credit: Wikimedia Commons — The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets – the Oort Cloud. Credit: Wikimedia Commons

“Objects on long-period orbits like this usually exhibit cometary tails, for example Comet ISON and Comet Hale Bopp, so we immediately knew this object was unusual,” stated Karen Meech, an astronomer at the University of Hawaii at Manoa who led the research. “I wondered if this could be the first evidence of movement of solar system building blocks from the inner solar system to the Oort Cloud.”

The automated Pan STARRS1 survey telescope found C/2013 P2 in August 2013, with astronomers remarking its orbit resembled that of a comet. But, C/2013 P2’s surface was quiet. A second look the next month with the 8-meter Gemini North telescope in Hawaii revealed a little bit of light and a dusty tail. The object stayed at about the same brightness, even when it got to its closest approach to the Sun (2.8 AU) in February 2014.

After the comet swung around the Sun and telescopes could look at it again, examinations with the Gemini North telescope found something weird: the object’s spectrum looked red. This makes it look more like a Kuiper Belt object — something that roams in shallower waters in the Solar System, beyond Neptune’s orbit — than a typical comet or asteroid.

While results were still being analyzed, in September a NASA survey found an object with curiously similar properties: C/2014 S3. When it was found, the object had already passed its closest approach to the Sun in August. But from analyzing the orbit, the scientists saw it had come to only within 2 AU. Also, the first observations showed barely a tail at all.

Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]

A closer examination with the Canada-France-Hawaii Telescope revealed a mystery: the spectrum was more blue than red, hinting at materials similar to what you would find in the inner Solar System. The team says this could be a new class of objects altogether.

“I’ll be thrilled if this object turns out to have a surface composition similar to asteroids in the inner part of the asteroid belt. If this is the case, it will be remarkable for a body found so far out in the Solar System,” stated Meech.

“There are several models that try to explain how the planets grew in the early Solar System, and some of these predict that material formed close to the sun could have been thrown outward into the outer Solar System and Oort Cloud, where it remains today. Maybe we are finally seeing that evidence.”

Results were presented today (Nov. 10) at the Division of Planetary Sciences meeting of the American Astronomical Society in Tucson, Arizona. A press release did not say if the research is peer-reviewed, or state publication plans.

Source: University of Hawaii Institute for Astronomy

February 28, 2014April 26, 2016 by Elizabeth Howell

Did An Icy Collision Produce The Odd Shape Of Asteroid 624 Hektor?

Artist's impression of 624 Hektor, the largest known Trojan asteroid. The dual asteroid is 155 miles (250 kilometers) at its widest. It also has a 7.5-mile (12-mile) moon. Credit: H. Marchis/F. Marchis

Two icy asteroids could have crashed into each other early in the solar system’s history to form the strange-looking 624 Hektor, new research reveals. The 155-mile (250-kilometer) asteroid is the largest known Trojan asteroid, or space rock that follows along with Jupiter in the gas giant’s orbital path.

Hektor also has a moon, which was first discovered in 2006 by another team led by the same lead author, the SETI Institute’s Franck Marchis. It’s taken the astronomers about eight years to get a handle on the complex orbit of the system, a topic that the new research examines in detail. That was partly because the path was so “bizarre”, the team stated, and also because time on the W.M. Keck Observatory telescopes (used to perform the observations) is limited. There are few other observatories that could do the same work, the team added.

The moon, which is about 7.5 miles or 12 kilometers in diameter, orbits its parent asteroid every three days. The moon’s path is about 373 miles (600 km) distant and inclined almost at 45 degrees to the asteroid’s equator.

The Trojan asteroid 624 Hektor is visible in these two adaptive optics observations in July 2006 and October 2008, both performed with the W.M. Keck Observatory's II telescope. Hektor is in the middle of each picture, and its moon in the circles. Credit: WMKO/Marchis — The Trojan asteroid 624 Hektor is visible in these two adaptive optics observations in July 2006 and October 2008, both performed with the W.M. Keck Observatory’s II telescope. Hektor is in the middle of each picture, and its moon in the circles. Credit: WMKO/Marchis

“The orbit of the moon is elliptical and tilted relative to the spin of Hektor, which is very different from other asteroids with satellites seen in the main-belt,” stated Matija Cuk, a paper co-author who is a scientist at the Carl Sagan Center of the SETI Institute. “However, we did computer simulations, which include Hektor being a spinning football shape asteroid and orbiting the Sun, and we found that the moon’s orbit is stable over billions of years.”

While the artist’s conception above shows Hektor as a peanut, the exact shape is still not known for sure. The models and the adaptive optics suggest that it is likely a dual-lobe asteroid. What is better known, however, is that the asteroid is “extremely elongated” and spins in less than seven hours.

The origin of the moon is unclear, but the researchers suggested it could be because of ejecta associated with the collision that formed the asteroid. They said more simulations are needed on that point. What’s more, Hektor has another mystery associated with its composition.

An artist's rendering of a Kuiper Belt object. Image: NASA — An artist’s rendering of a Kuiper Belt object. Image: NASA

“We also show that Hektor could be made of a mixture of rock and ices, similar to the composition of Kuiper belt objects, Triton and Pluto. How Hektor became a Trojan asteroid, located at only 5 times the Earth–Sun distance, is probably related to the large scale reshuffling that occurred when the giant planets were still migrating,” stated Julie Castillo-Rogez, a researcher at NASA’s Jet Propulsion Laboratory who participated in the research.

You can read more about the research in Astrophysical Journal Letters. By the way, the moon does not have a name yet, and the researchers said they are looking for any ideas as long as it fulfills a couple of ideas: “the satellite should receive a name closely related to the name of the primary and reflecting the relative sizes between these objects.” Feel free to share your suggestions in the comments.

Source: W.M. Keck Observatory

January 27, 2014December 23, 2015 by Nancy Atkinson

Trailer: New Horizons Gets Ready to Meet Pluto

Artist's impression of New Horizons' encounter with Pluto and Charon. Credit: NASA/Thierry Lombry

Less than a year from now, the New Horizons spacecraft will begin its encounter with Pluto. While closest approach is scheduled for July 2015, the Long Range Reconnaissance Imager or “LORRI” will begin snapping photos of the Pluto system six months earlier.

This first mission to Pluto has been a long time coming, and this new “trailer” put out by the New Horizons team recounts what it has taken to send the fastest spacecraft ever on a 5 billion km (3 billion mile) journey to Pluto, its largest moon, Charon, and the Kuiper Belt beyond. The spacecraft has been zooming towards the edge of our Solar System for over eight years since it launched on January 19, 2006.

By late April 2015, the approaching spacecraft will be taking pictures of Pluto that surpass the best images to date from Hubble. By closest approach in July 2015 –- when New Horizons will be 10,000 km from Pluto — a whole new world will open up to the spacecraft’s cameras. If New Horizons flew over Earth at the same altitude, it’s cameras could see individual buildings and their shapes.

“Humankind hasn’t had an experience like this–an encounter with a new planet–in a long time,” said Alan Stern, New Horizons’ principal investigator. “Everything we see on Pluto will be a revelation.”

It’s likely there could be some new planetary bodies discovered during the mission in addition to the five known moons: Charon, Styx, Nix, Kerberos, and Hydra.

“There is a real possibility that New Horizons will discover new moons and rings as well,” says Stern.

No matter what, Stern said, this is going to be an amazing ride.

“We’re flying into the unknown,” he said, “and there is no telling what we might find.”

See the countdown clock and find out more about the mission at the New Horizons website.

December 11, 2013March 14, 2017 by Fraser Cain

Where Should We Look for Life in the Solar System?

Emily Lakdawalla is the senior editor and planetary evangelist for the Planetary Society. She’s also one of the most knowledgeable people I know about everything that’s going on in the Solar System. From Curiosity’s exploration of Mars to the search for life in the icy outer reaches of the Solar System, Emily can give you the inside scoop.

In this short interview, Emily describes where she thinks we should be looking for life in the Solar System.

Follow Emily’s blog at the Planetary Society here.
Follow her on Twitter at @elakdawalla
And Circle her on Google+
Continue reading “Where Should We Look for Life in the Solar System?”

August 30, 2012April 26, 2016 by Jason Major

What Has the Kuiper Belt Taught Us About The Solar System?

Over 4 billion miles (6.7 billion km) from the Sun, the Kuiper Belt is a vast zone of frozen worlds we still know very little about. Image: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

Today marks the 20th anniversary of the discovery of the first Kuiper Belt Object, 1992QB1. KBOs are distant and mostly tiny worlds made up of ice and rock that orbit the Sun at incredible distances, yet are still very much members of our Solar System. Since 1992 over 1,300 KBOs have been found, and with NASA’s New Horizons spacecraft speeding along to its July 2015 rendezvous with Pluto and Charon (which one could argue are technically the first KBOs ever found) and then onwards into the Belt, we will soon know much more about these far-flung denizens of deep space.

But how has the discovery of the Kuiper Belt — first proposed by Gerard Kuiper in 1951 (and in a fashion even earlier by Kenneth Edgeworth) — impacted our current understanding of the Solar System? New Horizons Principal Investigator Alan Stern from the Southwest Research Institute recently discussed this on his mission blog, “The PI’s Perspective.”

First, Stern lists some of the surprisingly diverse physical aspects of KBOs that have been discovered so far:

Some are red and some are gray;
The surfaces of some are covered in water ice, but others (like Pluto) have exotic volatile ices like methane and nitrogen;
Many have moons, though none with more known moons than Pluto;
Some are highly reflective (like Pluto), others have much darker surfaces;
Some have much lower densities than Pluto, meaning they are primarily made of ice. Pluto’s density is so high that we know its interior is about 70% rock in its interior; a few known KBOs are more dense than Pluto, and even rockier!

But although these features are fascinating in themselves, just begging for further exploration, Stern notes that there are three very important lessons that the Kuiper Belt has taught us about the Solar System:

1. Our planetary system is much larger than we had ever thought.

“In fact, we were largely unaware of the Kuiper Belt — the largest structure in our solar system — until it was discovered 20 years ago,” Stern writes. “It’s akin to not having maps of the Earth that included the Pacific Ocean as recently as 1992!”

2. Planetary locations and orbits can change over time.

“This even creates whole flocks of migration of planets in some cases. We have firm evidence that many KBOs (including some large ones like Pluto), were born much closer to the Sun, in the region where the giant planets now orbit.”

3. Our solar system, and likely others as well, was very good at making small planets.

“Today we know of more than a dozen dwarf planets in the solar system, and those dwarfs already outnumber the number of gas giants and terrestrial planets combined. But it is estimated that the ultimate number of dwarf planets we will discover in the Kuiper Belt and beyond may well exceed 10,000. Who knew?”

And with a little jab at the whole Pluto-isn’t-a-planet topic, Stern asks: “And which class of planet is the misfit now?”

Read: Was Pluto Ever REALLY a Planet?

The discovery of the Kuiper Belt has shown us that our solar system — and very likely planetary systems across the galaxy, even the Universe — aren’t neat and tidy things that can be easily summed up with grade-school models or chalkboard diagrams. Instead they are incredibly diverse and dynamic, continually evolving and consisting of countless, varied worlds spanning enormous distances… yet still connected through the ever-present effects of gravity (not to mention the occasional-yet-unavoidable collision.)

“What an amazing set of paradigm shifts in our knowledge the Kuiper Belt has brought so far. Our quaint 1990s and earlier view of the solar system missed its largest structure!”

– Alan Stern, New Horizons Principal Investigator

Read more about the New Horizons mission here.

The first KBO identified, 1992 QB1 (European Southern Observatory)

April 27, 2012December 23, 2015 by Jason Major

Cassini Exposes Phoebe As More Planet Than Moon

Color-composite image of Phoebe as seen by Cassini in 2009.

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Saturn’s curious moon Phoebe features a heavily-cratered shape and orbits the ringed planet backwards at a considerable distance of over 8 million miles (12.8 million km). According to recent news from the Cassini mission Phoebe may actually be a Kuiper Belt object, having more in common with planets than it does with any of Saturn’s other satellites.

132 miles (212 km) in diameter, Phoebe is the largest of Saturn’s irregular moons — a cloud of small, rocky worlds held in distant orbits at highly inclined paths. Its backwards (retrograde) motion around Saturn and dense composition are dead giveaways that it didn’t form in situ within the Saturnian system, but rather was captured at some point when it strayed too close to the gas giant.

In fact it’s now thought that Phoebe may be a remnant from the formation of the Solar System — a planetesimal — with its own unique history predating its adoption into Saturn’s extended family of moons.

“Unlike primitive bodies such as comets, Phoebe appears to have actively evolved for a time before it stalled out,” said Julie Castillo-Rogez, a planetary scientist at NASA’s Jet Propulsion Laboratory. “Objects like Phoebe are thought to have condensed very quickly. Hence, they represent building blocks of planets. They give scientists clues about what conditions were like around the time of the birth of planets and their moons.”

Although Phoebe is heavily eroded and irregularly-shaped today at one time it may have been much rounder. But an early composition of radioactive elements would have generated heat, and as it warmed it “deflated” through compression, growing denser and denser.

640120main_pia15507-43_800-600 — Map of Phoebe's surface. (NASA/JPL-Caltech/SSI/Cornel)

Now, Phoebe exhibits a similar density to Pluto — another denizen of the Kuiper Belt.

At some point Phoebe may even have had water, kept liquid by its radioactive heat. That is, until the heat faded and it froze, creating the icy surface detected by Cassini’s instruments.

Still, Cassini’s study of Saturn’s moons has provided scientists with clues to what was happening much earlier on in the Solar System. What caused Phoebe to drift inwards to be caught up in orbit around Saturn? How did it survive such a supposed shuffling of planets and other worlds did not? As Cassini continues its investigation answers — and undoubtedly even more questions — will be uncovered.

Read more on NASA’s news release here.

Image: NASA/JPL/SSI. Color composition by Gordan Ugarkovic.

October 19, 2011December 24, 2015 by Nancy Atkinson

Evidence of a Late Heavy Bombardment Occuring in Another Solar System

This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Evidence for this barrage comes from NASA's Spitzer Space Telescope, whose infrared detectors picked up indications that one or more comets was recently torn to shreds after colliding with a rocky body. Image credit: NASA/JPL-Caltech

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Planetary scientists have not been able to agree that a turbulent period in our solar system’s history called the Late Heavy Bombardment actually occurred. But now, using observations from the Spitzer Space Telescope, scientists have detected activity resembling a similar type of event where icy bodies from the outer solar system are possibly pummeling rocky worlds closer to the star. This is the first time such activity has been seen in another planetary system.

“Where the comets are hitting the rocky bodies is in the habitable zone around this star, so not only are life-forming materials possibly being delivered to rocky worlds, but also in the right place for life as we know it to grow,” said Carey Lisse, senior research scientist at the Johns Hopkins University Applied Physics Laboratory. “This is similar to what happened to our own solar system during the Late Heavy Bombardment.”

Lisse spoke to journalists in a conference call from the Signposts of Planets meeting taking place at Goddard Space Flight Center this week.

Spitzer observations showed a band of dust around the nearby, naked-eye-visible star called Eta Corvi, located in the constellation Corvus in northern sky. Within the band of warm dust, Spitzer’s infrared detectors saw the chemical fingerprints of water ice, organics and rock, which strongly matches the contents of an obliterated giant comet, suggesting a collision took place between a planet and one or more comets. Also detected was evidence for flash-frozen rocks, nanodiamonds and amorphous silica.

This dust is located 3 AU away from Eta Corvi, which is the “habitable zone” around that star, and is close enough to the star that Earth-like worlds could exist. Lisse said although it hasn’t been confirmed, researchers think there is a Neptune-like world and at least two other planets in this system. A bright, icy Kuiper Belt-like region located 3-4 times farther out than our own Kuiper Belt was discovered around Eta Corvi in 2005.

“This is very possibly a planet-rich system,” Lisse said.

The light signature emitted by the dust around Eta Corvi also resembles meteorites found on Earth. “We see a match between dust around Eta Corvi and the Almahata Sitta meteorites, which fell to Earth in Sudan in 2008,” Llisse said. “We can argue that the material around Eta Covi is rich in carbon and water, things that help life grow on Earth.”

The Eta Corvi system is approximately one billion years old, which the research team considers about the right age for such a bombardment.

No asteroidal dust was found in the disk around Eta Corvi.

“Asteroidal dust would look like it had been heated, and chemically and physically altered, and most of the water and carbon would be gone,” Lisse said. “This dust is very rich in water and carbon and the rocky components are very primitive and un-altered.”

Most planetary formation theories can’t account for such an intense period of bombardment in our own solar system so late in its history, but the Nice Model proposed in 2005 suggests the Late Heavy Bombardment was triggered when the giant planets in our solar system— which formed in a more compact configuration – rapidly migrated away from each other (and their orbital separations all increased), and a disk of small asteroids and comets that lay outside the orbits of the planets was destabilized, causing a sudden massive delivery of asteroids and comets to the inner solar system. The barrage scarred the Moon and produced large amounts of dust.

“We can see the process of this happening at Eta Corvi and can learn more about our own solar system, since we can’t go back in time,” Lisse said. “It’s very possible that the rain of comets and Kuiper Belt Objects brought life to Earth.”

Lisse and his team are not sure if one big comet or lots of smaller comets are pummeling the inner solar system. “It is probably many bodies, but we only see the effects of the largest ones,” he said.

Could this be an indication that a Late Heavy Bombardment happens in many solar systems? “It’s not clear whether this is an atypical system, but we do know of one other possible system where it could be happening,” Lisse said in response to the question posed by Universe Today. “I think this is a rare event, which might mean that life is rare if you need a Late Heavy Bombardment for life to happen.”

Lisse said the reason they studied this star was the earlier detection of the Kuiper Belt-like region around Eta Corvi. “We knew it was an exceptional system from previous infrared sky surveys and the large bright Kuiper Belt was just the tip of the iceberg,” Lisse said. “This system was shouting, ‘I’m something extraordinary, come figure out my mystery!”

Paper: Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in Eta Corvi at ~1 Gyr

Source: Signposts of Planets conference call, JPL Press release